Whale Galaxy Panorama

The vague wedge shape of galaxy NGC 4631—with the broad area on the left tapering down to a blue tail on the right—led to its popular moniker: the Whale galaxy.

The “head” of the whale here is the galactic center, which is lit up with star birth and gas heated from supernova explosions. This bright light silhouettes bands of dense, darker material that lie between the Whale and us.

Toward the tail there is less dust but still areas of bright blue star formation, driven by interactions with neighboring galaxies. As gas and dust from different galaxies meet in space, denser areas are created, which gravity compacts into new stars.

This is a spiral galaxy seen from the side, or edge-on. This is similar to how we view the Milky Way from our position inside it—we see one of the spiral arms stretching across the sky. The Whale galaxy is actually similar in size to the Milky Way; the area we are seeing here is about 140,000 light-years across.